MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6
MIPS R6 removed quite a few R2 instructions. However, there
is plenty of <R6 userland code so we add an in-kernel emulator
so we can still be able to execute all R2 userland out there.
The emulator comes with a handy debugfs under /mips/ directory
(r2-emul-stats) to provide some basic statistics of the
instructions that are being emulated.
Below are some statistics from booting a minimal buildroot image:
Instruction Total BDslot
------------------------------
movs 236969 0
hilo 56686 0
muls 55279 0
divs 10941 0
dsps 0 0
bops 1 0
traps 0 0
fpus 0 0
loads 214981 17
stores 103364 0
llsc 56898 0
dsemul 150418 0
jr 370158
bltzl 43
bgezl 1594
bltzll 0
bgezll 0
bltzal 39
bgezal 39
beql 14503
bnel 138741
blezl 0
bgtzl 3988
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 883eb3a..afa808a 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2063,6 +2063,19 @@
default y
depends on MIPS_MT_SMP
+config MIPSR2_TO_R6_EMULATOR
+ bool "MIPS R2-to-R6 emulator"
+ depends on CPU_MIPSR6 && !SMP
+ default y
+ help
+ Choose this option if you want to run non-R6 MIPS userland code.
+ Even if you say 'Y' here, the emulator will still be disabled by
+ default. You can enable it using the 'mipsr2emul' kernel option.
+ The only reason this is a build-time option is to save ~14K from the
+ final kernel image.
+comment "MIPS R2-to-R6 emulator is only available for UP kernels"
+ depends on SMP && CPU_MIPSR6
+
config MIPS_VPE_LOADER
bool "VPE loader support."
depends on SYS_SUPPORTS_MULTITHREADING && MODULES